Hello there!
The reason I write is that since I installed the Setsugen on my Sapphire HD4870 I can hear a cheeping sound when the card is under load.
Whenever I start a demanding software such as Folding @ Home or Furmark the card immediately starts the sound, when the application is closed, the sound is gone. It's not very loud, but high. As all my fans run at low speed even under full load (and all components are well temperatured), the sound is very noticeable from inside my case which has a rather breezy design.
Of course, I don't blame the Setsugen, it's a great cooler.
Although I had to add an extra VRM-Cooler from a competitor because the tiny self-adhesive coolers didn't do the job too well. Just hope to find an expert here, who could point me to the source of the sound and if I could do something about it...